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<head><meta charset="utf-8"><title>prefix ? · t-compiler/help · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/index.html">t-compiler/help</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/prefix.20.3F.html">prefix ?</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/prefix%20%3F/near/225265714" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Mario Carneiro <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/prefix.20.3F.html#225265714">(Feb 05 2021 at 06:28)</a>:</h4>
<p>I see some lines like <a href="https://github.com/rust-lang/rust/blob/master/compiler/rustc_trait_selection/src/traits/select/mod.rs#L603"><code>debug!(?result);</code></a> in the compiler, is this a nightly feature or something rustc specific, or specific to the <code>debug!</code> macro?</p>



<a name="225266779"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/prefix%20%3F/near/225266779" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/prefix.20.3F.html#225266779">(Feb 05 2021 at 06:54)</a>:</h4>
<p>it’s tracing’s debug macro</p>



<a name="225362946"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/prefix%20%3F/near/225362946" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Noah Lev <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/prefix.20.3F.html#225362946">(Feb 05 2021 at 21:55)</a>:</h4>
<p>Specifically, the <code>tracing</code> crate.</p>



<a name="225363022"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/prefix%20%3F/near/225363022" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Noah Lev <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/prefix.20.3F.html#225363022">(Feb 05 2021 at 21:56)</a>:</h4>
<p>I think it's roughly equivalent to <code>debug!("result={:?}", result);</code>. It's funny though, because I've never seen it in the compiler before.</p>



<a name="225363864"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/prefix%20%3F/near/225363864" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> nagisa <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/prefix.20.3F.html#225363864">(Feb 05 2021 at 22:03)</a>:</h4>
<p>grep for sigil in <a href="https://docs.rs/tracing/0.1.23/tracing/">https://docs.rs/tracing/0.1.23/tracing/</a> for docs</p>



<a name="225363956"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/prefix%20%3F/near/225363956" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Mario Carneiro <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/prefix.20.3F.html#225363956">(Feb 05 2021 at 22:04)</a>:</h4>
<p>thanks</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/prefix%20%3F/near/225367660" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> lqd <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/prefix.20.3F.html#225367660">(Feb 05 2021 at 22:39)</a>:</h4>
<p><a href="https://docs.rs/tracing/0.1.23/tracing/macro.debug.html">https://docs.rs/tracing/0.1.23/tracing/macro.debug.html</a></p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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